The paper investigates evolutionary stability conditions of the class of signaling games with the following properties: (a) the interests of sender and receiver coincide, (b) different signals incur differential costs, and (c) different events (meanings/types) have different probabilities. The main finding is that a profile belongs to some evolutionarily stable set if and only if a maximal number of events can be reliably communicated. Furthermore, it is shown that under the replicator dynamics, a positive measure of the state space is attracted to "sub-optimal" equilibria that do not belong to any asymptotically stable set.